同学你好，该知识点来自沪江网校《BEC商务英语中高级【四项全能实战签约班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学好
我们来划分以下句子结构：
1. A course (that has been co-developed in this way) ensures that trainees will study relevant and correct information.
这句话是一句宾语从句。本句中主语：A course    谓语：ensures   宾语：that trainees will study relevant and correct information
第一个that并不是充当主语，that has been co-developed in this way都是作后置定语修饰course，这里不能省略that是因为在定语成分里也有谓语动词has been, 如果去掉that，这句话就会出现2个谓语动词(has been和ensures)，在语法上是不成立的。

2. Many off-site, instructor-led programs (which删除) provide learning labs for trainee practice
主语：programs，谓语动词：provide，宾语：learning labs   目的状语：for trainee practice
这里主谓宾结构已经完整，显然这个which是多余的。如果不删除要修改一下句子，
变成：Many off-site, instructor-led programs (which provide learning labs for trainee practice) are very popular.
这种情况下主语: programs   谓语动词变成：are     宾语：very popular    定语：which provide learning labs for trainee practice  这个时候which就不可以删除了

综上，要判断关系代词(which/who/that)等是否需要删除，还是要先分析句子的主谓宾结构。

希望能帮助到你，祝学习愉快！